1. Field
Embodiments described herein relate generally to an electrically-rewritable nonvolatile semiconductor memory device and a writing method thereof.
2. Description of the Related Art
There is a rapid increase in demand for NAND type flash memory along with increase of mobile device applications that process large-size data such as images, motion pictures, etc. Especially, by employing a multi-value storage technique that enables information of two bits or more to be stored in one memory cell, NAND type flash memory has become able to store more information with a smaller chip area.
In a highly-integrated flash memory with a high degree of miniaturization of cells, data threshold distributions are influenced by interference between adjoining cells. Particularly, when a multi-value storage scheme is employed, the width of data threshold distributions and the interval between the distributions are set smaller than those of a two-value storage scheme. Therefore, interference between adjoining cells greatly influences data reliability.